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Electrical conduction in Ba(Bi0.5Nb0.5)O3 ceramics. Impedance spectroscopy analysis

Prasad K., Bhagat S., Amarnath K., Choudhary S. N., Yadav K. L.

Materials Science Poland

2010

Vol. 28, No. 1

317--325

A new lead free perovskite ceramics Ba(Bi0.5Nb0.5)O3 was fabricated by a conventional ceramic technique at 1185 °C and subsequent sintering at 1200 °C in air atmosphere. The XRD analysis of Ba(Bi0.5Nb0.5)O3 powder indicated the formation of a single-phase monoclinic structure. The ac conductivity data were found to obey the power law and showed a negative temperature coefficient for the resistance behaviour. The ac conductivity values were used to evaluate the density of states at the Fermi level, minimum hopping length and activation energy of the compound. The correlated barrier hopping model was found to successfully explain the mechanism of charge transport in Ba(Bi0.5Nb0.5)O3.

Electrical properties of 0.90Pb[(Mg,Zn)1/3Ta2/3]O3-0.10PbTiO3 relaxor

Prasad S., Prasad K., Choudhary S.N., Sinha T.P.

Materials Science Poland

2008

Vol. 26, No. 3

475--485

Polycrystalline 0.90Pb[(Mg2/3Zn1/3)1/3Ta2/3] O3-0.10PbTiO3 having a tetragonal perovskite type structure was prepared by the high temperature solid-state reaction method. Dielectric studies showed the relaxor behaviour with diffuse phase transition. High value of ∈max > 10000 was realized with the temperature of the permittivity maximum (Tm) around room temperature at 1 kHz. The frequency dependence of Tm has been modeled using Vogel-Fulcher relation. The dielectric relaxation in the present system was found analogous to the magnetic relaxation in spin-glass system. The shape of the complex impedance curve indicated that the system exhibited almost Debye type dielectric relaxation at 350 °C, where as non-Debye character was observed at temperatures ≥ 325 °C. Further the relaxation frequency was found to shift towards higher frequencies with an increase in temperature.